Researchers from the University of Amsterdam and the Max Planck Institute for Chemical Ecology, including Dr. Astrid Groot (UvA-IBED), found that the specialist moth Heliothis subflexa benefits from the defensive compounds of the Physalis to give a boost to its own immune system. The results were published in the journal Nature Communications.

Insects versus plants in evolutionary arms race

In order to survive and to repel herbivores, many plants defend themselves by producing toxic or deterrent substances. In the course of evolution, many insects have succeeded in adapting to the defensive chemistry of their host plants, thereby circumventing plants’ defense mechanisms. However, the plants have also adapted their defensive system to further protect themselves against their enemies, which, in turn, generated counter-adaptations in the insects, and so forth. Biologists refer to this phenomenon as an 'evolutionary arms race' between plants and insects.

Many insects are plant pests which can be categorized as specialists or generalists. Whereas generalists feed on many different plants, specialists have adapted to one or few closely related plant species as their food. The moth species Heliothis subflexa analyzed in this new study is such a specialist that feeds on Physalis.

Unique benefit to specialisation

The study shows that the Heliothis subflexa benefits from withanolides, a defensive compound in Physalis plants that usually acts as immune suppressant and feeding deterrent in insects. Surprisingly, the moth uses these plant defenses as immune-system boosters. Moreover, withanolides protect the moth from harmful effects caused by pathogenic bacteria. The study hereby demonstrates a unique benefit to host-plant specialisation.